Hitherto, an injection foaming and molding operation using an injection molding machine has been performed in a manner such that a heated and plasticized foaming resin is rapidly injected and filled into a mold cavity, a surface of a molded product contacting a mold is cooled and solidified after the resin injecting and filling operation, and a gap between molds is widened to reduce the internal pressure of the molded product and foam and expand the inside of the molded product. Due to such an injection foaming and molding operation, a molded product may be obtained which has a good appearance and is light and tough.
A foaming resin molding machine of the related art shown in PTL 1 will be described. The injection foam molding machine is a molding machine in which four sets of movable mold moving mechanisms are provided at either a movable mold platen or a fixed mold platen. In the movable mold moving mechanism, a nut is linearly moved by a screw driven by a servo motor, and one end surface of the nut comes into contact with the other mold platen so that the molds move away from each other. When the movable mold is moved in the mold opening direction by the mechanism, the movable mold is slightly opened while applying a load in the mold closing direction using a mold opening and closing mechanism or a mold fastening mechanism.